The objective of this project is to develop the existing gas target neutron source to the point where it is capable of being utilized for patient treatment. Our goal is to provide clinically useful dt neutron beam of 20 rads per minute at 125 cm SSD. To achieve this goal the present source output must be doubled and the system operation modified to increase the unit reliability. The installation of a suitable neutron shield will be followed by construction and installation of a fixed field collimator. We plan to utilize only a fixed horizontal beam. Pertinent measurements will be made of the resulting neutron beam. The thrust of these measurements will be to form a basis permitting delivery of a radiotherapeutic neutron dose. Characteristic depth dose and isodose curves from the beam will be obtained as well as measurements of the effect source diameter and SSD of the source. Measurements will also be made of the gamma ray contamination and the strength of the neutron source as a function operating time. Following these physical measurements experiments will be conducted to characterize the radiobiological characteristics of the beam and to permit a comparison with the cyclotron neutrons currently in use. Radiobiology studies will also establish normal tissue tolerance for this particular neutron beam and collimation system. BIBLIOGRAPHIC REFERENCE: A Tritium Gas Target As An Intense Source Of 14 MeV Neutrons, Chenevert, G.M., DeLuca, P.M., Kelsey, C.A., and Torti, R.P., Nucl. Instr. and Methods, 1977, in press.